Vindhyan supergroup

Vindhyan supergroup

1. Vindhyan Supergroup

2. 1.Introduction 2.Stratigraphy 3.Economic mineral 4.Conclusion C ontents

3. Vindhyan basin is named after the Vindhyan Mountains Covers an exposed area of 60,000sq.km and a concealed area of 1,62,000km.sq under the Indo- Gangetic Alluvium and Deccan Trap The strata are exposed in Son valley, Bundelkhand and Rajasthan The Son –Narmada fault bound the basin in the south and the Great Boundary Fault in the northwest Geographically, it starts from Sasaram in the east to Dholpur in the north Introduction

4. Vindhyan basin belongs to mesoproterozoic It is sickle shape, ENE trending situated on the Bundelkhand craton Cont…

5. Vindhyan supergroup can be divided into two viz … upper Vindhyan and lower Vidhyan , composed of sandstone, shale and carbonate, few conglomerate and volcanoclastic bed Lower vindhyan is 1,300-1,100M.y, marine in origin consisting of calcareous and argillaceous sediments Upper vindhyan is 1,000-600my, fluviatile in origin and exclusively arenaceous Stratigraphy

6. Upper Vindhyan enclose two diamond bearing horizon, from which Panna and Golconda diamonds have been mined The upper and lower Vindhyan supergroup are seperated by unconformity, prominent in the North but almost disappears in the Southern areas. Cont….

7. Lower Vindhyan Semri group- 3000 to 4000m thickness Derived its name from Semri river well developed in the eastern Son valley It rests with non-conformity on Bundelkhand Irregular thickness indicates irregular basin floor It is made up of five alternating formations of shale and carbonates with areas of sandstones and volcanic clastic units Basal succession consist of conglomerate, cross bed ferruginous sandstone and shale Pb-Pb isochron age is 1750-1500Ma Lithology

8. Kaimur group- Seperated from the lower Vindhyan by unconformity 400m thickness Named after kaimur scarp It is essentially made up of sandstone-shale Ripple marks and sun cracks are found on the shales In Bundelkhand it shows a basal conglomerate containing pebbles of jasper Using Rb-Sr isochron the age is 1100-1150Ma Upper vindhyan

9. Rewa group Named after the Rewa state Thickness 100-300m Sediments thickens to the north indicating deepening of the basin Seperated from kaimur by a zone of diamond bearing conglomerate Consist of a series of shales and sandstones formations that, in areas contain kimberlite derived diamondiferous conglomerates The presence of mud crack suggest periodical exposures and the presence of rain prints in the shale indicates sub aerial conditions

10. Cont… The basal Panna shale without any basal conglomerate indicates continuity of deposition from Kaimur group. Bhander group Named after Bhander upland, extensively developed along the axis of the basin and in the Bhopal inlier within the Deccan trap Thickness is 1300-1500m Seperated from the Rewa group by a horizon diamond bearing conglomerate Bhander sandstone are fine grained and soft

11. The Ganurgarh shale with stromatolitic limestone indicates shoreline lagoon-tidal flat complex The top unit of Maihar sandstone unit is a blanket deposit with ripple marks, cross bedding and load-cast indicating tidal flat to near shore littoral environment. Cont…

12. Diamond,pyrite,coal,limestone,building and decorative stones are reported from Vindhyan basin Diamond have been reported in the conglomerate in Panna The limestone of Vindhyans are among the most important sources of raw materials for the lime and cement industry in India Vindhyan sandstone near U.P on disintegrating by weathering yield good sands which are being used for the manufacture of glass. Economic importance

13. Pyrite is reported from the Bijaigarh shales of lower Kaimur.The material is of good quality, contaning around 45% sulphur , without any arsenic. Cont…..

14. Vindhyan basin, also called Purana basin is one of the important mesoproterozoic basin (1,600-1,000Ma ). In Rewa group, some formation of shales and sandstones contain diamoniferous conglomerates. The presence of coal intercalations indicates the existence of plants in Kaimur and Semri group though there is no workable coal seam The evidence of life is either direct or indirect Direct evidence-mega and micro fossils e.g., Chuaria and Tawuia Indirect evidence- stromatolites , algal mats etc conclusion

15. Vindhyan supergroup is the thickest Precambrian sedimentary succession of India and duration of its deposition is the longest. Cont….

16. 2010,Geology of India, M.Ramakrishnan and R.Vaidyanadan , Geological society of India, pp464-471 1983,Geology of India, D. N. Wadia,Published byTata McGraw-Hill Publishing Company Limited pp121-131 http://en. wikipedia.org/wiki/ vindhyan supergroup Reference

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